JP2844697B2 - Manufacturing method of low-dust polycarbonate molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to the production of dust having a size of 0.5 to 1.0 μm in a molded product.
Low dust polycarbonate molded product of 10 × 10 ⁴ or less,
In particular, it is a method for producing low-dust polycarbonate molded products that generate less dust such as metals and pyrolysis products (hereinafter abbreviated as burnt) during the injection molding process. The cylinders and screws of the injection molding machine are made to have specific corrosion resistance and abrasion resistance. This is a method for producing a low-dust polycarbonate molded article in which an increase in dust due to burns and inclusion of foreign metal in an injection molding process is suppressed by using a material made of a conductive material.

[Conventional technology and its problems]

Recently, polycarbonate has been widely used for applications such as optical disks, lenses, and optical waveguides.
In addition, conventional general applications have been extended to thinner precision molded products utilizing the heat resistance, transparency, safety, dimensional stability, mechanical strength, and the like of polycarbonate resins.

Among these applications, in applications where transparency is essential, particularly in optical applications, dust contained in the molded product, that is, so-called foreign matter, is a factor that hinders its function.

For this reason, much research has been made on reducing dust in the raw material polycarbonate resin. However, little attention has been paid to differences in contamination due to the material of the injection molding machine during the injection molding process, and burns and metals in molded products are also considered to be based on the thermal stability of the raw material polycarbonate and other differences. The tendency was large.

In conventional injection molding, the amount of dust of the raw material polycarbonate was large, and the injection molding conditions were much milder than those of recent applications, so dust generation during the injection molding process may be negligible. Almost. Therefore,
The challenge for resin manufacturers was to first clean the raw material polycarbonate.

For resin raw material manufacturers and their users, the injection molding machine is appropriately selected from the models provided by the specialized manufacturer, there is no room to consider the contents, and there is no necessity in the past, There is no knowledge that the injection molding machine maker changes the dust amount of the injection molded product depending on the material used, and furthermore, these molded products are manufactured through a much more severe molding process compared to the past. It was hard to say that it had been considered.

On the other hand, experience has shown that carbon steel catalytically promotes the above gelation reaction of polycarbonate resin. Then, when the molten polycarbonate resin is brought into contact with a low-alloy steel SACM steel (Al-Cr-Mo steel), which is a kind of ordinary carbon steel, a brown resin is formed on the steel surface. In severe cases, it was confirmed that the product changed to black.The brown or black product was insoluble in halogenated hydrocarbons, which are good solvents for polycarbonate resin. It was presumed that it was a gelled product which had been reticulated and further carbonized. In addition, such a product greatly increases even when molding is performed in a dust-controlled clean environment and the raw material polycarbonate resin is supplied in a completely closed system.

From the above, it is clear that most of the dust in the low-dust polycarbonate molded product was newly generated in the process of re-melting and plasticizing solid polycarbonate inside the injection molding machine, and low-dust polycarbonate. It was presumed that in order to manufacture a molded product, it is essential to use a molding machine, particularly a material of a type that generates less dust.

However, a material which can be used for a cylinder or a screw of an injection molding machine and which generates little dust and can be processed economically has not been found.

[Means for solving the problem]

Accordingly, the present inventors have conducted intensive studies on the relationship between the material of the backflow prevention ring provided at the tip of the cylinder or screw or the screw of the injection molding machine and the generation of dust. According to the molding machine, it was found that dust generation was significantly reduced, and based on this, the present invention was reached.

That is, the present invention relates to a method for producing a molded polycarbonate article by injection molding using powder or pellets of a polycarbonate resin, wherein an inner peripheral surface of the injection molding machine is made of a corrosion-resistant and wear-resistant alloy comprising the following alloy component (1). A member formed by hard chrome plating or Ni kanigen plating on carbon cylinder and carbon steel formed (Kanigen is a registered trademark of Nippon Kanigen Co., Ltd.
A method for producing a low-dust polycarbonate molded product, characterized by using an injection molding machine using any one of SUS420, SUS440 or a steel material comprising the following alloy component (2) as a screw member.

Alloy component (1); C: 0.5 to 1.5% by weight Si: 1.0 to 2.0% by weight B: 0.5 to 2.5% by weight Ni: 10.0 to 20.0% by weight Cr: 20.0 to 30.0% by weight W: 10.0 to 20.0% by weight Cu: 0.5 to 2.0% by weight Remainder: Co and inevitable impurities. Alloy component (2); C: 0.5 to 1.5% by weight Cr: 10.0 to 20.0% by weight Mo: 1.5 to 2.5% by weight V: 0.5 to 1.5% by weight Fe: 75.0 to 85.0% by weight 5.0 × 10 ⁴ dust particles of 0.5 to 1.0 μm in powder or pellet
/ g or less, the screw body of the injection molding machine is made of either carbon steel, hard chrome plating or Ni Kanigen plating, SUS420, SUS440 or an alloy component (2), The backflow prevention ring, the part in contact with the ring, and the tip of the screw must be made of SU420, SUS440 or a steel material composed of alloy component (2), and the injection molded product made of polycarbonate is an optical disk or a lens. This is a method for producing a characteristic low-dust polycarbonate molded product.

 Hereinafter, the configuration of the present invention will be described.

First, with the polycarbonate resin of the present invention, a dihydric phenol as a monomer, a phosgene method, a transesterification method,
An aromatic polycarbonate resin produced by bonding a dihydric phenol to a carbonic acid ester by the pyridine method or the like. Most commonly, bisphenol A [= 2,2-bis (4-hydroxyphenyl) propane; Described below) as a monomer, but also includes a transparent resin such as a graft copolymer of the polycarbonate and another resin. In addition, various polycarbonate-based resin compositions can be suitably applied from the effect of reducing generation of burns and the like in the injection molding process.

Since the present invention is for producing a low-dust polycarbonate molded product, the aromatic polycarbonate resin pellets or powder to be used are naturally low-dust products corresponding to the dust level requirements of the intended molded product. It is necessary.

Usually, dust in the polycarbonate resin material powder exists according to a specific particle size distribution and has a size of 0.5 to 1 μm.
If m dust is reduced to 5.0 × 10 ⁴ particles / g or less, 1 to 10 μm; 1000
Pcs / g or less and 10 to 50 μm;
Accordingly, dust having a size of 0.5 to 1 μm in the powder or pellets of the polycarbonate resin of the present invention is preferably used.
5.0 × 10 ⁴ pieces / g or less. In particular, for optical applications such as optical disks and lenses, the density is preferably 1.0 × 10 ⁴ pieces / g or less.According to the present invention, it is possible to obtain a molded product of 2.0 × 10 ⁴ pieces / g or less. , Error rate and reliability under a long-term high-temperature, high-humidity environment.

The inner peripheral surface of the cylinder and the surface of the screw of the injection molding machine of the present invention, that is, the material of the portion in contact with the molten aromatic polycarbonate resin is made of the specific steel material as described above.

The cylinder can be entirely made of the alloy of the above-mentioned alloy component (1), but the above-mentioned alloy is expensive,
Also, since machining is extremely difficult, SCM440, SNCM43
9. It is preferable to form a high strength steel material such as SUS304 or SUS316 as a back metal and form the above alloy layer on the inner peripheral surface thereof.
The method for forming the alloy layer is not particularly limited, but a typical example thereof is preferably a HIP method using powder metallurgy.

Further, as the screw, a member manufactured by using at least a member obtained by hard chromium plating or Ni Kanigen plating on carbon steel, SUS420, SUS440, or a steel material comprising the above-mentioned alloy component (2) is used. In addition, in the part where the load is large in the injection molding process, the plated member has low impact strength, so if the plating is peeled off and the base is exposed, the dust increases significantly due to burns and the like, and the metal contamination due to the peeled plating layer It is not preferable because it causes.
Therefore, the backflow prevention ring at the tip of the screw, which is a part with a large load, and the part in contact with the ring and the tip of the screw are made of either SUS420, 440 or a steel material composed of the above-mentioned alloy component (2), especially the alloy component ( 2)
It is preferable to use one manufactured from a steel material consisting of

Furthermore, the inner surface of the nozzle at the tip of the molding machine and the molten resin flow path of the mold should be made of either hard chrome plating or Ni Kanigen plating, alloy component (1) or (2), or SUS420 or SUS440. Is preferred.

It should be noted that even in stainless steel, austenitic materials such as SUS304, 316, and 310 easily cause burns when brought into contact with a molten polycarbonate resin.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples and the like.

Example 1 and Comparative Example 1 An injection molding machine having a cylinder and a screw made of an alloy having a composition shown in the following alloy component list in Table 1 was used.

The screw diameter of the injection molding machine was 28 mm and the injection capacity was 3 ounces. In the embodiment, the tip portion of the screw (that is, the backflow prevention ring and the portion in contact with the ring, the tip portion of the screw) were all the screws shown in Table 1. It is made of material 2. In addition, the screw member of the test No. 3 of the comparative example, the screw body is subjected to Ni plating,
The backflow prevention ring, the portion in contact with the ring, and the tip of the screw are made of SACM steel of screw material 5 shown in Table 1.

Using these injection molding machines, polycarbonate resin for optical use (trade name; Iupilon H-4000: manufactured by Mitsubishi Gas Chemical Co., Ltd.), pellets at a resin temperature of 320 ° C., a mold temperature of 80 ° C., and a molding cycle of 24 seconds. An optical disc substrate having a thickness of 1.2 mm and a diameter of 130 mm was molded in a clean room of class 1000, and the results of measurement of dust on the disc at the 200th shot after the start of molding are shown in Table 2 below.

In addition, the measurement of the number of dust
A solution dissolved in 100 cc of methylene chloride was measured using a light scattering particle size sensor.

Example 2 and Comparative Example 2 In Example 1, injection molding was performed for the case where the cylinder 2 and the screw 4 were used (Example 1-3) and the case where the cylinder 1 and the screw 4 were used (Comparative Example 1-3). Stop once, keep the cylinder temperature at 320 ° C, leave it for 2 hours, then start injection molding again, sample the disk every 50 shots and count the dust (size 0.5 ~
Table 3 shows the results of measuring the change over time of 1.0 μm).

From Table 3, it can be seen that in the case of the injection molding machine using the material of the present invention, the dust level was rapidly reduced, stable operation was possible, and the increase in the number of dusts from the raw material pellets was 0.5%.
It is understood that the material having a thickness of about 1.0 μm is stable at 0.3 to 0.5 × 10 ⁴ pieces / g. On the other hand, in the case of the conventional material, the attained dust level is poor and the variation is large.

Example 3 and Comparative Example 3 Using an injection molding machine having a screw diameter of 45 mm and an injection capacity of 5 oz, a cylindrical molded artificial dialyzer housing having a diameter of 5 cm, a length of 30 cm and a thickness of 1.5 mm was molded at a resin temperature of 300 ° C. At a mold temperature of 100 ° C. and a molding cycle of 30 seconds, when the screw material of the molding machine was the same as in Example 1-2 (cylinder 2, screw 3), it was compared with Comparative Example 1-1 (cylinder 1, screw 1). Moldings were produced for the same case.

Table 4 shows the results of measuring the number of dusts and the number of white spots having a diameter of 50 μm or more after steaming at 125 ° C. for 100 hours.

The polycarbonate resin used was Iupilon S-3000R manufactured by Mitsubishi Gas Chemical Co., Ltd.
Size 0.5-1 μm; 4.5 × 10 ⁴ pieces / g, 1-10 μm; 560 pieces / g,
10-50 μm: 0 / g.

From the results shown in Table 4, it is understood that not only an increase in the number of dusts due to excuse deterioration in the injection process can be suppressed, but also a molded article excellent in hydrolysis resistance can be obtained.

[Action and Effect of the Invention]

As described above, according to the method for producing a low-dust polycarbonate molded product using an injection molding machine using a cylinder and a screw of a specific material in the contact portion with the resin of the present invention, an increase in dust in the injection molding process is caused. It is clear that this is greatly reduced. From this, it is understood that this is an extremely effective method for manufacturing molding materials for optical products that require a high level of dust reduction. It can be understood that the reduction of the physical property deterioration based on the decomposition deterioration is achieved and is extremely significant.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-188675 (JP, A) JP-A-59-25941 (JP, A) JP-A-60-5869 (JP, A) JP-A-2- 208015 (JP, A) JP-A-59-83753 (JP, A) JP-A-53-147632 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 45/00-45 / 84

Claims (4)

(57) [Claims] 1. A method for producing a polycarbonate molded product by injection molding using powder or pellets of a polycarbonate resin, wherein an inner peripheral surface of the injection molding machine is formed of a corrosion-resistant and wear-resistant alloy comprising the following alloy component (1). Hard chrome plating or Ni kanigen plating on carbon cylinders and carbon steel (Kanigen is a registered trademark of Nippon Kanigen Co., Ltd .; omitted hereafter), SUS420, SU
A method for producing a low-dust polycarbonate molded product, characterized by using an injection molding machine using S440 or a steel material comprising the following alloy component (2) as a screw member. Alloy component (1); C: 0.5 to 1.5% by weight Si: 1.0 to 2.0% by weight B: 0.5 to 2.5% by weight Ni: 10.0 to 20.0% by weight Cr: 20.0 to 30.0% by weight W: 10.0 to 20.0% by weight Cu: 0.5 to 2.0% by weight Remainder: Co and inevitable impurities. Alloy component (2); C: 0.5 to 1.5% by weight Cr: 10.0 to 20.0% by weight Mo: 1.5 to 2.5% by weight V: 0.5 to 1.5% by weight Fe: 75.0 to 85.0% by weight 2. The method according to claim 2, wherein the number of dust particles of 0.5 to 1.0 μm in the powder or pellets of the polycarbonate resin used in said injection molding is 5.0.
The method for producing a low-dust polycarbonate molded product according to claim 1, wherein the amount is × 10 ⁴ / g or less. 3. The screw body of the injection molding machine is made of a member made of hard chromium plating or Ni kanigen plating on carbon steel, and a backflow prevention ring and a portion contacting the ring and a screw tip are made of SUS420, SUS440 or alloy. The method for producing a low-dust polycarbonate molded article according to claim 1, wherein the molded article is produced from any one of the steel materials comprising the component (2). 4. The method for producing a low-dust polycarbonate molded article according to claim 1, wherein the polycarbonate molded article is an optical disk or a lens.